Pressure tank

What is the difference between a hydronic pressure tank and a potable pressure tank? Can a hydronic tank be used for drinking water?

No only equipment for potable water can be used for potable water....

What is the difference in the tanks?

Excuse my ignorance, are we speaking of expansion tanks¿

I have gotten a expansion tank that I would like to use as a pressure tank at a camp I have. It will be mostly for washing dishes and a shower. We use bottled water for drinking and cooking. Is here some reason an expansion tank can't be used as a pressure tank?

The expansion tank does not have the capacity that a well tank would have...

As far as potability issues...

The components of a heating system do not have to protect the quality of the water as it is a closed loop behind a backflow prevention device and will hopefully never end up in your potable water supply.

Take trip over to the drain on your heating system and drain some water into a glass. Take a look at it and see how tasty it looks...

Be thankful that the expansion tank on your potable water system is constructed of materials safe for use with potable water.

A visit to
http://www.watts.com
or,
http://www.amtrol.com/
reading may answer your questions on materials used.